Update FXBlurView.m

Added support for dynamically choosing the rendering method based on the presence of an SKView in the stack
Update FXBlurView.h

Added property to track presence of SKView in the stack
Properly obfuscated the SKView reference to be backward compatible.
Provided a method to clear out the layer.  This is helpful if we want the blur view to be clear for a while after it has shown a blurred image
Merge branch 'master' of https://github.com/MobileVet/FXBlurView
oops, bug in my obfuscation… we were checking against an id, not a class
Very bad allocation by Rob.....
Merge remote-tracking branch 'upstream/master'

Conflicts:
	FXBlurView/FXBlurView.m
Superview is now a property, underlyingView
Merge branch 'master' of https://github.com/CrowdTunes/FXBlurView